Electric circuit-breaker



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Sept. l, 1931. A. ALLAN ELECTRIC CIRCUIT BREAKER Filed Jan. 25, -1950Patented Sept. 1, 1931 UNITED STATES PATENT oFFiCE ARCHIBALD` ALLAN, FTYNEMOUTH, ENGLAND, ASSIGNOR TO A. REYROLLE & COM- PANY LIMITED, 0I'HEBBURN-ON-TYNE, ENGLAND, A COMPANY OF GREAT BRITAIN ELECTRICCIRCUIT-BREAKER Appiicatidn med January 25, 1930, serial No.

This invention relates to electric circuitbreakers and more particularlyto the contactsthereof. v

The object of the 1 invention is the conu struction of an improved formof contact of the general type in which a spring-pressed arcing contactis arrangedy to slide relatively to one or more main contacts.

A Contact for an electric circuit-breaker according` to the presentinvention comprises one or more main contacts, an arcing contactslidable axially against the action of a spring in guides which formsupports for the main contacts, and a dashpot having a piston whichtowards the end of the closing movement of the circuit-breaker is movedinwards in the dashpot by the movement of the sliding contact.

fThe improved contact is primarily intended for use in an oil-immersedcircuitbreaker, vand one construction is illustrated in the accompanyingdrawings, in which Figure 1 is an elevation with the casing in section,

Figure 2 is a vertical central section on the line 2-2 of Figure l,

Figure 3 a view similar to Figure 2 but with the parts in a positionwhich they occupy during part of the closing movement 3o of thecircuit-breaker, and

Figure 4 is a sectional plan on the line 1 -4 of Figure 1.

Like letters indicate like parts throughout the drawings.

In these iigures, the blocks A, of which there are six, constitute oneof the main relatively fixed contacts of an oil-immersedcircuit-breaker. The cooperating movable contact is shown only in Figure3 at B.

The main contact blocks A are supported on springy arms as at A1 on ablock C1 forming part of a slotted tube C attached to or integral with aiixed plate D to which one of the conductors (not shown) lead- 15 ing tothe circuit-breaker can be connected by the clamp E.

Slidable in the block C1 is an arcing contact F having a head F1 whichis screwed into a crosshead G guided in the slotted tube 56 C andelectrically connected to the plate D 423,443, and in Great BritainMarch 26, 1929.

by flexible conductors G1. A spring H encircles the slotted tube Cbetween the fixed plate D and the crosshead G, thus exerting a pressurewhich tends to keep the crosshead and arcing contact down in thepositions shown in Figures l and 2.

Fixed in the upper part of the tube C is a dashpot J having slidingwithin it a piston J1 pressed down by a spring K. There is a smalloutlet for oil from the dashpot through a screwed plug L passing throughthe plate D. To this plate D is secured a shield or casing M whichsurrounds all the parts and extends down. somewhat below the maincontact blocks A. As will be seen by reference to Figure l, the shapeand disposition of the parts are such that in the open position of thecircuit-breaker the lower ends of the shield M and the slidable arcingcontact F are bounded by an imaginary sphere indicated by the line X.

The block C1, as may be seen from Figure l, is in this example hexagonalfor convenience in attaching to it the arms and springs which supportthe blocks A.

The movable main contact B is not shown in Figures 1 and 2 where therelatively fixed main contacts A and the arcing Contact F are in theopen position. In Figure 8 the movable main Contact B has been broughtupwards in the usual closing movement of the circuit-breaker and, asshown, it has pressed the sliding arcing contact F upwards through itsguide block C1 and is beginning to spread the main contact blocks A.This upward movement of the arcing contact has carried the crosshead Gupwards in the slotted guide tube C against the action of the spring Hand the'head F1 has pushed the piston J1 up into the dashpot J against90 the action of the spring K. This movement is not necessarily completein the position shown in Figure 3 but may be continued somewhat furtheraccording to the upward travel of the movable main contact B. As thehole in the plug L is small an effective cushioning or dashpot action isexercised on the moving parts towards the end of the closing movement ofthe circuit-breaker. On

J(he opening movement the arcing Contact m" can, under the action of thespring H, follow freely the downward movement of the main contact B asit is independent of the dashpot and its piston.

It is to be understood that the construction illustrated is given by wayof example and that details may be varied within the scope of theinvention as set forth in the appended claims. y n

That I claim as my invention and desire to secure by Letters Patentis 1. In an electric circuit-breaker a contact comprising an arcingcontact slidable axially in a guide or support, at least one maincontact mounted on said support, a spring acting on said arcing Contact,a dashpot in the path of motion of the arcing contact, and a piston insaid dashpot said piston being separate from the arcing cont-act so thatit is engaged and moved inwards in the dashpot towards ythe end of theclosing movement of the circuit-breaker but permits free movement of thearcing vcontact during the opening ot' the circuit-breaker.

2. In an electric circuit-breaker an arcing contact slidable axially ina slotted support, a plurality of spring-mounted main contacts attachedto said support, a crosshead on said arcing contact and guided in theslots in said support, a spring acting on said crosshead, a dashpot inthe path of motion of the arcing contact, a piston in said dashpot, anda spring acting on said piston said piston being separate from Vthearcing cont-act so that it is engaged and moved inwards in the dashpottowards the endV of the closing movement of thel circuit-breaker butpermits free movement of the arcing contact during the opening of thecircuit breaker.

3. In an electric circuit-breaker a contact comprising a supportingplate, a slot-ted guide attached to said plate, an arcing contactslidable axially in said guide, a plurality of spring-mounted maincontacts surrounding said arcing contact, a crosshead on said arcingcontact and working in said slotted guide, a spring acting on Saidcrosshead, a dashpot in the path oi motion of the arcing contact, apiston in said dashpot, a spring acting on said piston said piston beingseparate from the arcing contact so that it is engaged and moved inwardsin the dashpot towards the end of the closing movement of thecircuit-breaker but permits free movement of the arcing contact duringthe opening of the circuit breaker, and flexible connections betweensaid cross* head and the supporting plate.

4. In an electric circuit-breaker an arcing contact slidable axially ina slotted support., a plurality of spring-1nounted main contactsattached to said support, a crosshead on said arcing contact and guidedin the slots in 5 said support, a spring acting on said crosshead, adashpot in the path of motion of the arcing contact, a piston in saiddashpot, a spring acting on said piston said piston being moved inwardsin the dashpot towards the end of the closing movement of thecircuit-breaker, and a casing surrounding the contacts and having anopen end extending almost to the lower end of the arcing contact so thatin the open position of the circuit-breaker the lower ends of the casingand arcing contact are bounded by the surface of an imaginary sphere.

5. In an electric circuit-breaker a contact comprisingV a supportingplate, a slotted guide attached to said plate, an arcing contactslidable axially in said guide, a plurality of springLmounted maincontacts surrounding said arcing contact, a crosshead on said arcingcontact and working in said slotted guide, a spring act-ing on said'crosshead, a dashpot in the path of motion of the arcing contact, apiston in said dashpot, a spring acting on said piston said piston beingmoved inwards in the dashpot towards the end of the closing movement ofthe circuit-breaker, flexible connections between said crosshead and thesupporting plate, and a casing surrounding the contacts and having anopen end extending almost to the lower end of the arcing contact so thatin the open position of the circuit-breaker the lower ends of the casingand arcing contact are bounded by the surface of an imaginary sphere.

In testimony whereof I have signed my name to this specification.

ARCHIBALD ALLAN.

